Concrete Foundation Walls
Structural Deterioration And Damage
Problem: Cracks and spalling from poor construction practices - 2.
Cause: Over watering.
The addition of 1 gallon (4 L) of water to 1.3 cubic yards (1 cubic meter) of concrete will decrease its strength by more than 145 psi (1 MPa) and increase slump by 1 foot as shown in Figure 7
Figure 7 - Effects of Overwatering
Solutions: Never add water on the construction site
- Adding water alters the water-cement ratio on the mix, resulting in a loss of strength and the potential for increased shrinkage and reduced durability and water tightness.
- Where workability and movement of concrete around the site is expected to be a problem, use pumped concrete, or have the supplier increase the slump of the concrete by changing the proportions of aggregate, by adding a super-plasticizer, or by increasing the percentage of air entrainment.
- Pour basements from a number of entry points to minimize the need to "flow" the concrete around the forms.
- Shovel or pump out wet sites to prevent standing water and mud from mixing with the poured concrete. Concrete should be placed on undisturbed soil or well compacted fill.